Given the abstract class , RentableDwelling, containing: a (private ) double instance variable , rentPerUnit a constructor accepting a double used to initialize rentPerUnit a method , getRentPerUnit that returns the value of rentPerUnit an abstract method getRentalIncome that returns a double write a (non-abstract) subclass, ApartmentHouse, containing: an int instance variable numberOfApartments a constructor accepting a double , passed to the superclass constructor , and an int used to initialize numberOfApartments the method getRentalIncome calculated as the product of numberOfApartments and the rent per unit. getRentalIncome returns a double.

LANGUAGE: JAVA

CHALLENGE:

Given the abstract class , RentableDwelling, containing:
a (private ) double instance variable , rentPerUnit
a constructor accepting a double used to initialize rentPerUnit
a method , getRentPerUnit that returns the value of rentPerUnit
an abstract method getRentalIncome that returns a double
write a (non-abstract) subclass, ApartmentHouse, containing:
an int instance variable numberOfApartments
a constructor accepting a double , passed to the superclass constructor , and an int used to initialize numberOfApartments
the method getRentalIncome calculated as the product of numberOfApartments and the rent per unit. getRentalIncome returns a double.

SOLUTION:

public class ApartmentHouse extends RentableDwelling {
    private int numberOfApartments;
    public ApartmentHouse (double rentPerUnit, int numUnits) {
        super(rentPerUnit);
        numberOfApartments = numUnits;
    }
    public double getRentalIncome() {
        return(getRentPerUnit()*numberOfApartments);
    }
}